The overall objective of this work is produce an "Atlas of Human Bone Mechanical Properties". This atlas will document site specific, orthotropic elastic moduli, shear moduli, Poisson's ratios, densities, and structure of the cortical and cancellous regions of the femur, tibia, patella, humerus, radius, mandible, and thoracic and lumbar vertebrae. Elastic properties will be measured from several sites on each bone using a previously developed ultrasonic technique. Bones inlcuded in the study will be from four normal and four severely osteopenic human cadavers, with the determination of osteopenia will be made primarily by a transiliac biopsy. Such information is necessary and vital for the development of accurate finite element models of the skeletal system. Finite element modeling (FEM) is an important tool for the analysis of the mechanical response of biologic tissue to external forces. The versatility of FEM allows complicated geometry, as well as inhomogeneous and anisotropic material properties, to be easily incorporated into models of the skeletal system. With the increased availability and decreased price of more powerful computational hardware, combined with more sophisticated and less expensive software, very powerful modeling capabilities are becoming available to a large number of researchers for analyses of the effects of bone loss and prosthetic design.